1. Field of The Invention
The present invention relates to an electrical connector assembly, and particularly to an electrical connector assembly for directly connecting two printed circuit boards together which has an improved electromagnetic inferference/radio frequency interference (EMI/RFI) protection.
2. The Prior Art
A board-to-board connector assembly is used for directly connecting a daughter board to a mother board, without the necessity of using an auxiliary device such as a cable.
FIGS. 6 and 7 show a conventional board-to-board connector assembly including a receptacle connector 1 and a plug connector 2. The receptacle connector 1 consists of a dielectric housing 11, a number of contacts 14 (only one shown), a pair of shields 12 and a pair of solder pads 13. The housing 11 is formed to have a generally rectangular configuration with a bottom face 18 for proximity to the plug connector 2, a top face 19 for proximity to a mother board (not shown), a channel 111 exposed to the bottom face 18, a number of contact passageways 112 beside the channel 111, a pair of solder pad mounting ears 15 projecting laterally near the top face 19 and each defining a solder pad receiving recess 151 fixedly receiving a corresponding solder pad 13, and a number of shield mounting blocks 113 on a front and rear side (not labeled) of the housing 11 near the bottom face 18. Each shield 12 is configured to have a number of alternating engaging tabs 121 and lugs 122 near a lower edge thereof. Each engaging tab 121 is interferentially engaged between two corresponding shield mounting blocks 113. Each lug 122 has a bead 123 projecting toward the housing 11. Each shield 12 further forms a number of fingers 124 at an upper edge thereof projecting into corresponding contact passageways 112 to connect with corresponding contacts 14 connecting with a grounding circuit of the mother board. The solder pads 13 are soldered to the mother board to enhance the fastening of the receptacle connector 1 to the mother board.
The plug connector 2 consists of an elongate dielectric housing 21, two solder pads 24, a number of contacts 22 and a number of auxiliary contacts 214. The housing 21 is formed with an outer wall 210 defining a number of auxiliary contact passageways 213, a central ridge 211 located within the outer wall 210, and two solder pad mounting ears 23 at lateral ends of the housing 21 fixedly receiving the two solder pads 24, respectively. The central ridge 211 defines two rows of contact passageways 212 in a front and rear face (not labeled) thereof, respectively. The contacts 22 are fixedly received in the contact passageways 212, and the auxiliary contacts 214 are fixedly received in the auxiliary contact passageways 213. Furthermore, each auxiliary contact 214 has a portion contacting a corresponding contact 22 connecting with a grounding circuit of a daughter board (not shown). The solder pads 24 are soldered to the daughter board to enhance the fastening of the plug connector 2 to the daughter board.
When the receptacle and plug connectors 1, 2 are assembled, the central ridge 211 extends into the channel 111 so that the contacts 22, 14 of the plug and receptacle connectors 1, 2 are electrically connected together. The beads 123 on the lugs 122 of the shields 12 of the receptacle connector 1 extend into the corresponding auxiliary contact passageways 213 to contact with the corresponding auxiliary contacts 214 of the plug connector 2, whereby the connector assembly can be protected from EMI/RFI by the shields 12.
However, such a conventional board-to-board connector assembly does not shield two lateral ends of the housing 11 of the receptacle connector 1, which results in incomplete protection of the assembly from EMI/RFI. Furthermore, the connector assembly requires many components which increases manufacturing costs. Furthermore, the grounding circuit of the daughter board is only connected to the grounding circuit of the mother board via the connection between the auxiliary contacts 214 and the beads 123. Such a connection is inadequate to ensure a reliable transmission of noise received by the plug connector 2 to the grounding circuit of the mother board. Finally, as each shield 12 has an excessively large surface/thickness ratio, it cannot have a rigidity sufficient to ensure the flatness thereof. The lower edge of each shield 12 may deflect away from the housing 11 when it is mounted thereto, which causes the beads 123 to improperly contact (or even disengage from) the auxiliary contacts 214 of the plug connector 2, thereby unfavorably affecting the shielding effectiveness designed to be achieved by the shields 12.
Hence, an improved board-to-board connector assembly is needed to eliminate the above mentioned defects of the conventional board-to-board connector assembly.